Based on the premise that perception is a continual series of simple hypotheses about the external world which are built up and selected by sensory experiences, this book explores in detail some of the major findings in perception and speculates about interconnections between sensory experiences, brain function, perception, and language and thought. Topics covered include objects and pictures; reversals and distorting figures; scaling the universe; drawing in two and three dimensional space; pictures, symbols, thought and language; and seeing how things work. Some evidence is offered for the author's suggestion that the brain function man has inherited from his biological past has been fundamentally modified by the uniquely human invention of symbols and that logical problem solving is gradually divorcing man from the way brains work. It is suggested that with technological development, man must adapt to what he is creating or run the risk of creating a world beyond the restraints of his own intelligence. (RH)